View Full Version : MH intensity/Kelvin loss plus Daylight-actinic combo

s a v v o
08/20/2002, 02:53 AM

Thanks very much for a very informative and helpful article on lighting for the average person like me.

I have a couple of queries I hope you can help me with.

After a year's use, my two Venture MH 150w 10,000K bulbs have lost that blue-white, crisp look.

Are there any studies that indicate

(a) the level of loss of intensity after such a period, and

(b) how much the colour temperature changes, and to what extent.

The kind of info that would be of interest to me would be, for example, that the 150w "output" drops to, say, 100w (it probably doesn't work that way!!), and that the colour temp drops from 10,000K to, say, 7,000K (this probably doesn't work that way either!!!).

The second question involves the combination of daylight and actinic fluoros, which you say gives a colour temp of 10,000K. Similar to my first question, how does the intensity/colour change after, say, 6-12 months of use (given the usual photoperiod of about 12 hours per day).

Looking forward to your reply.

Kind regards,

Les Savage (S a v v o)

08/30/2002, 11:35 PM
Hi Les,

I am very sorry that I could not reply sooner.

One of the best references that I have used when looking for general information and information on intensity and spectrum loss are the articles below from Sanjay Jpshi and Dave Morgan in AFM Online.

Part 1


Part 2


It is somewhat hard to determine when our bulbs have reached the end of their useful lives without specialized, costly tools. When I was running only VHO on my 75g tank, I replaced the bulbs every six to nine months where as on my 55g tank I have been using the bulbs for over a year now without issues from what I can see by looking at my coral health.

From reading the articles above, I have about 13 months on my 400 watt 6500k Iwasaki bulbs at this time and I plan to replace them over the next month. In addition, it seems that the higher Kelvin bulbs do loose both spectrum and intensity faster then the lower Kelvin bulbs and if I were using them, I would consider replacing them every nine months to one year based on the experience of the other members on Reef Central.


s a v v o
09/02/2002, 12:10 AM

Thanks for your reply. I'll look at those sites you referred me to.

Best regards,